A removable hard disk case generally includes a hard disk, a fan, a detection circuit and a enclosure-control chip. The detection circuit is used to detect the temperature, the fan's rotation speed and the voltage. The enclosure-control chip is used to collect environmental parameters and transmit them back to a host controller. A removable hard disk case of the conventional ATA (also called IDE) interface is generally connected to the host controller via a parallel ATA (PATA) bus. Using the PATA as the transmission interface, the enclosure-control chip in the removable hard disk case can transmit environmental parameters back to the host controller. The host controller also controls the enclosure-control chip in the removable hard disk case and transmits data to the hard disk via the PATA. An LED lamp is also directly connected to the enclosure-control chip in the removable hard disk case to flash when the hard disk malfunctions or is active.
Nowadays, the ATA interface evolves from parallel bus to serial bus, wherein two pairs of 1.5 GHz cables are used to transmit data at a higher speed. However, because the speed is as high as 1.5 GHz, if other external components are connected, there will be a problem of signal attenuation. Therefore, the 1.5 GHz cable can hardly be connected externally to other enclosure-control chips, or even the 1.5 GHz cable can be connected externally to other enclosure-control chips, the cost will be high. Generally, a channel of a host is connected to the hard disk via the serial ATA (SATA). The host controller is additionally connected to the LED lamp and the enclosure-control chip. However, the corresponding relation between the channel of the host and the enclosure-control chip disappears. That is, the corresponding relation between the hard disk connected to the channel and the LED lamp disappears. This will derives the following problem. When one hard disk malfunctions, the user cannot determine the hard disk corresponding to the flashing lamp. For instance, if a host controller has four serial ATA channels and can connect four hard disks, each accompanying a enclosure-control chip. Each of the enclosure-control chips has its ID. The host controller is series connected with the four enclosure-control chips via I2C interface. When the host controller finds that the hard disk of channel 1 malfunctions, it needs to let the LED lamp corresponding to channel 1 flash to notify the user to replace the hard disk. However, because the corresponding between the channel of the host and the enclosure-control chip disappears, unless the software has the capability of detecting the corresponding between the channel of the host and the ID of the enclosure-control chip, one can only assume the external wiring is the same as in the program. For instance, the program fixes the ID of the enclosure-control chip connected with channel 1 to 1, when the system performs the setting, the user must connect the cable of channel 1 to the removable hard disk case with ID 1 manually. However, manual assignment of ID easily connects wrong enclosure-control chips, resulting in the problems of incorrect flashing light and incorrect removal of hard disk.
Accordingly, the present invention aims to propose a hard disk device capable of detecting channels of a host to which hard disk controllers belong so as to build the corresponding relations between the channels of the host and the hard disk controllers.